The present invention relates to an axial conveyor which is suitable in particular for the transport of liquid/gas dispersions, preferably with a self-priming gassing agitator, and a loop reactor containing the axial conveyor.
Axial conveyors generally comprise, within a conveying channel taking the form of a tubular section, a drivable axle with obliquely pitched, wall-sweeping conveying vanes or screws. In the course of transport by means of axial conveyors, and in the direction of transport, a pressure zone develops below and a suction zone develops above the vanes or screws. The pressure gradient that is formed as a result in the gap between conveying tube (housing) and vanes or screws brings about a backflow of the medium to be conveyed. In the case of the transport of liquid/gas dispersions, separation of gas bubbles occurs as a result of the gap and hence, the conveying capacity falls. This effect is further intensified by virtue of the fact that the angular momentum impressed upon the liquid by rotation of the screw or of the vanes is retarded by the wall friction, so that the gas bubbles in the vicinity of the wall segregate in the direction towards the wall and coalesce on the wall. In the case of relatively high gas contents, this results in the collapse of the conveying capacity.
Axial conveyors are therefore suitable only for the transport of liquid/gas dispersions having gas contents of up to 5 vol-%.
An axial conveyor for conveying gas/liquid dispersions, comprising conveying elements, in a substantially cylindrical conveying tube, wherein said conveying elements are selected from the group consisting of propellers, vanes or screws disposed on a drivable axle, whereby said conveying elements comprise a wall-sweeping lip. A process comprising conveying gas/liquid dispersions as well as a process for carrying out chemical reactions comprising directly reacting gas with gases not completely dissolved in a liquid medium in an axial conveyor is also disclosed